I. Field of the Invention
Embodiments of this invention are directed generally to biology, medicine, and immunotherapy. In certain aspects, the present invention relates to the generation of double-loaded (RNA loaded and antigen loaded) antigen presenting cells (APCs) and their use in immunotherapy.
II. Background
Dendritic cells are the master regulators of the adaptive immune response (Banchereau and Palucka, 2005; Banchereau et al., 2003; Hartgers et al., 2000; Steinman et al. 2003), and the development of a dendritic cell vaccine that can consistently eliminate minimal residual neoplastic disease remains an important goal in the field of tumor immunology. In the design of dendritic cell vaccines for active cancer immunotherapy, a variety of tumor-specific agents have been used as antigen sources including tumor lysates (Chang et al. 2002; Geiger et al., 2001; Nestle et al., 1998), preparations of tumor mRNA (Heiser et al., 2002; Nair et al., 2002; Morse et al., 1999; Gilboa and Vieweg 2004), tumor specific peptides (Banchereau et al., 2001; Toungouz et al., 2001; Tjoa et al., 1998), idiotype protein (for myeloma or lymphoma) (Timmerman et al., 2002; Titzer et al., 2000; Lim et al., 1999) and gene transfer vectors expressing tumor-specific antigens (Tozer et al., 2002; Haluska et al., 2000). Of these agents, both tumor lysates and mRNA preparations are attractive antigenic sources as each possesses a full complement of patient-specific tumor antigens; however, each of these agents is also associated with its own particular biological shortcoming. The use of mRNA as an antigen source alone does not provide exogenous material for CD4+ T-cell priming, the consequence of which could be tumor-specific T-cell lethargy rather than robust CTL priming (Tham et al., 2002; Behrens et al., 2004; Rocha and Tanchot, 2004). Correspondingly, the use of lysate as an antigen source alone does not load the classical MHC class I compartment and might not efficiently provide antigenic material for CD8+ T-cell priming. When lysate is used as an antigen source, the phenomenon of dendritic cell cross-presentation is cited as the principal mechanism by which exogenous antigens are presented by MHC class I. While cross-presentation clearly plays a bona fide role in the generation of tumor-specific CTL, recent reports now demonstrate that cross-presentation may be somewhat biased in vivo and, perhaps, a suboptimal substitute for genuine, endogenous class I presentation (Wolkers et al. 2004; Zinkemagel 2002; Ochsenbein et al., 2001).
There remains a need for additional dendritic cell vaccine methodology and compositions.